Pump piston

ABSTRACT

A single-acting pump having an elastomeric and synthetic fabric piston seal ring and means to supply fluid to the piston to cool and clean the piston and cylinder.

United StHtES Patent 1 1 1 11 3,72%140 Lee 1March 13, 1973 PUMP PISTON 1[56] References Cited Inventor: Larry E. Lee, HOUStOn, TEX. UNITEDSTATES PATENTS Assign: Industries 2,545,506 3/1951 Walsh ..92/87 xHouston. x 2,677,581 5/1954 Taylor, Jr. ..277/l88 [22] Filed: M817 1971'3,104,619 9/1963 Swarthout ..92/87 [21] App]. No.1 173,506 PrimaryExaminer-Martin P. Schwadron Assistant ExaminerA. Hershkovitz 52 U.S.c1. ..92/s7, 92/240, 277/71, Kuwa 51 rm. c1 ..F0lb31/00 [57] ABSTRACT[58] Field of Search ..92/87, 240, 244; 277/227, 233, A single-actingpump having an elastomeric and 277/71 synthetic fabric piston seal ringand means to supply fluid to the piston to cool and clean the piston andcylinder.

1 Claim, 3 Drawing Figures PATEF-HFUHARISIFJH 3,720,140

' SHEET 1 [1F 2 LARRY E. LEE

I N VENTOR.

y ry Wm ATTORNEY LARRY E. LEE

INVENTOR.

PUMP PISTON SUMMARY This invention relates to pump pistons for use inmud or slush pumps used in connection with petroleum well drillingapparatus, pipeline, mining and related industries, and particularly toa piston having an elastomeric seal ring including synthetic materialfabric and fluid means for washing, cooling and lubricating the pistonand the wall of the cylinder or liner in which it operates.

In double-acting pumps, the piston is flooded on both sides, as is theliner, with the fluid being pumped, whereas, in a single-acting pump,only the working face of the piston is so flooded so that on the backstroke of the piston abrasive substances may be on the liner, and thewall thereof may be relatively dry, which can result in abrasive wear onthe piston, seal ring and liner wall, and which may result in excessiveheating of these parts particularly in modern high speed pumps.

It is an object of this invention to provide a new and improved pistonfor a single-acting pump, which piston employs an elastomeric seal ringhaving synthetic material fabric which has a relatively low operatingtemperature limit but which gives superior results over other pistonseals when supplied with the new and improved fluid circulating systemof the invention.

My invention has other objects and advantages some of which, with theforegoing, will be set forth in the description which follows.

I BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is fragmentary sectional viewof a single-acting pump showing the piston in operating position in aliner.

FIG. 2 is an enlarged view, partly in axial section, of the pump andpiston shown in FIG. 1. 1

FIG. 3 is an enlarged view, partly in axial section, showing anotherembodiment of the invention.

DESCRIPTION OF THE PREFERRED- EMBODIMENTS Referring to FIGS. 1 and 2, apump piston cylinder assembly is shown comprising a single-acting pistoncarried by a piston rod 11 and adapted for reciprocation within acylinder or liner 12. The piston 10 includes a piston head 13 having anaxially extending cylindrical portion 14 and a radially extendingannular flange 15. The piston rod 11 has a reduced threaded rod 11 mayhave wrench flats 23 thereon to hold the rod with a wrench while the nut18 is being applied to or removed from the rod. The rod 11 has a flange24 which is adapted to be connected to a power source which is showngenerally at 25. The piston head 13 has a groove 26 into which isdisposed a seal ring 27 to effect sealing between the end 16, the head13 and the flange 17.

The seal ring 20 may comprise generally an elastomeric material such asBuna-N or, other suitable material, having molded therein a fabric 26which may comprise: a regular weave or square woven nylon fabric orother suitable synthetic material.

The periphery of flange 15 when new has a small diametral clearance withthe wall of the liner 12 of preferably about two and one-halfthousandths to about seven and one-half thousandths of an inch. Theflange 15 has an annular groove 28 in its periphery. A radiallyextending hole 29 is drilled inwardly from the bottom of the groove 28.Another hole 30 is provided in flange 15 to intersect hole 29 andthereby establish communication with the annular groove 28. A tube 31 issecured in the hole 30. Seal means 31a is provided between the wall ofthe hole 30 and the tube 31. The tube 31 may be secured to the pistonrod 11 by means of clamps 32. A flexible conduit 33 is connected at oneend to the tube 31 and connected at its other end to a pressure sourceof fluid, which may be water or other suitable fluid. As can be seen inFIG. 1, the flexible conduit permits the piston to be moved from itsrearward position, as shown, to a forward position, moving a distanceindicated at 34.

Another embodiment of the invention is shown in FIG. 3, which is similarto that shown in FIGS. 1 and 2, except that fluid supply in thisembodiment is carried through flexible conduit which is threadedlysecured into piston rod 41, communicating with passageways 42 and 43.The flange 44 of piston head 45 has passageways 46 communicating withpassageway 43 and an annular groove 47 in the periphery of flange 44.

In operation, fluid in sufficient volume under ample pressure is forcedbetween the piston flange and cylinder to form a continuous film offluid behind the piston. This fluid film cools, cleans and lubricatesthe seal ring and cylinder and helps to prevent air and foreign materialfrom being drawn into the working chamber by the piston on its backstroke.

The fluid forced through the small clearance between the piston flangeand cylinder is more efficient, more uniformly distributed, and lessfluid is required than an open spray system which directs a stream ofliquid onto the back side of the piston.

The fabric 26, which is preferably nylon or the like molded into theseal ring 20, is much superior to the cotton fabrics previously used insuch pump piston seals because it has higher tensile strength, a lowercoefficient of friction and a good ability to stretch before breaking.Such a seal will have greatly increased field performance if it can bekept sufficiently cool in operation. Nylon or the like is much more heatsensitive than cotton fabric, but its other properties, as abovementioned, make such a nylon-reinforced seal very desirable especiallyfor use in modern high speed pumps. With the cooling arrangement of myinvention, such seal has been proven to be superior in actual field use.

While the embodiments of the invention as herein disclosed constitutepreferred forms, it is to be understood that other forms may be adoptedwithin the scope of the appended claims.

What is claimed is:

1. In a pump having a cylinder,

a single acting piston operative in said cylinder,

said single acting piston including an axially extending cylindricalportion terminating in an enlarged radially extending annular flangeportion, said cylindrical portion having an external diameterconsiderably less than the internal diameter of said cylinder and saidannular flange portion having a diameter commensurate with the internaldiameter of said cylinder,

a single elastomeric sealing ring positioned upon the cylindricalportion of said piston in abutting engagement with said annular flangeportion.

a member carried by said cylindrical portion and engaging said sealingring to retain same in engagement with said flange, readily releasablemeans clamping said member and sealing ring upon said

1. In a pump having a cylinder, a single acting piston operative in saidcylinder, said single acting piston including an axially extendingcylindrical portion terminating in an enlarged radially extendingannular flange portion, said cylindrical portion having an externaldiameter considerably less than the internal diameter of said cylinderand said annular flange portion having a diameter commensurate with theinternal diameter of said cylinder, a single elastomeric sealing ringpositioned upon the cylindrical portion of said piston in abuttingengagement with said annular flange portion. a member carried by saidcylindrical portion and engaging said sealing ring to retain same inengagement with said flange, readily releasable means clamping saidmember and sealing ring upon said cylindrical portion of said piston,said sealing ring having a sliding engagement with the inner surface ofsaid cylinder, said annular flange portion having a Circumferentialfluid passageway provided in the peripheral surface thereof, saidannular flange portion having fluid passageways communicating with saidcircumferential fluid passageway to conduct a fluid to the inner surfaceof said cylinder proximate said sealing ring and flange portion to forma continuous film of fluid behind said piston for cooling and cleaningthe cylinder and sealing ring.